Sudden flooding in Nepal has affected a number of operational and under-construction hydropower projects in Rasuwa and Nuwakot districts, with authorities carrying out rescue operations and assessing damage to electricity infrastructure.
Nepal’s Ministry of Energy, Water Resources and Irrigation issued a press release on 26 August providing preliminary information on damage caused by the flooding to electricity and other physical infrastructure.
The Ministry said it is coordinating search and rescue and relief operations, the restoration of electricity supplies and other activities in affected areas.
In Rasuwa district, five major operational hydropower projects with a combined capacity of 236MW and three projects under construction totalling 342.42MW have been affected.
The Ministry listed the affected projects as the 216MW Upper Trishuli-1, 111MW Rasuwagadhi, 120MW Rasuwa Bhotekoshi, 78MW Sanjen Khola, 6.42MW Upper Mailung A, 5MW Mailung Khola, 20MW Langtang Khola and 22MW Chilime hydropower projects.
Projects have also been affected in neighbouring Nuwakot district. The Ministry said four operational projects with a combined capacity of 123MW and two projects under construction totalling 52.6MW have been impacted.
The projects identified are the 24MW Trishuli, 14.1MW Devighat, 60MW Upper Trishuli-3A, 37MW Upper Trishuli-3B and 15.6MW Middle Trishuli Ganga hydropower projects, together with a 25MW solar project.
The Nepal Electricity Authority has mobilised a technical team to restore electricity services in areas where supplies have been interrupted.
Rescue operations are also continuing. The Ministry said details are being collected on employees, workers and local residents who have been out of contact as a result of the flooding.
Seven Nepal Electricity Authority vehicles have been deployed for rescue operations, with a further 14 vehicles on standby. A Ministry official has also been sent to the affected area to coordinate and facilitate rescue work, while coordination is underway for aerial rescue operations.
The Ministry also reported disruption to flood monitoring infrastructure. Around 200,000 SMS alerts had been sent to people in downstream areas warning of the possibility of flooding. However, damage to a gauge station has subsequently made it more difficult to obtain and provide further information on the flood risk.
Flood cause under investigation
The cause of the sudden flooding has not yet been definitively established.
Nepal’s National Disaster Risk Reduction and Management Authority (NDRRMA) said a preliminary analysis of satellite imagery indicated that an ice-rock landslide occurred around 20km northeast of the Rasuwagadhi border crossing between Nepal and China. The landslide is thought to have triggered a debris-laden flood in the Lhende Khola, which flows into the Bhotekoshi river system.
Nepal’s Department of Hydrology and Meteorology has also said that there was no heavy rainfall in the Rasuwa area immediately before the flood. The Department said a glacial lake outburst in Nepal or Tibet was among the possible causes being investigated but had not been confirmed.
A magnitude 4.4 earthquake was recorded in the Tibetan region shortly before the flooding. However, authorities have not established whether the earthquake caused or contributed to the landslide and subsequent flood.
Investigations into the sequence of events and the precise cause of the flood are continuing.
Meanwhile, Nepal’s Ministry of Energy, Water Resources and Irrigation said relevant authorities have been instructed to collect detailed information on damage to the affected projects and carry out technical assessments.
The Ministry said further restoration and reconstruction arrangements will be made on the basis of the information received. A committee has also been established to collect and evaluate details of the damage and prepare plans for rehabilitation.
The Ministry’s assessment remains preliminary and the press release does not provide an estimate of the financial damage to the affected hydropower projects.
